opentracing -> opencensus (#802)

* update vendor directory, add go.opencensus.io

* update imports

* oops

* s/opentracing/opencensus/ & remove prometheus / zipkin stuff & remove old stats

* the dep train rides again

* fix gin build

* deps from last guy

* start in on the agent metrics

* she builds

* remove tags for now, cardinality error is fussing. subscribe instead of register

* update to patched version of opencensus to proceed for now TODO switch to a release

* meh

fix imports

* println debug the bad boys

* lace it with the tags

* update deps again

* fix all inconsistent cardinality errors

* add our own logger

* fix init

* fix oom measure

* remove bugged removal code

* fix s3 measures

* fix prom handler nil

vendor/go.opencensus.io/plugin/ocgrpc/trace_common.go

@@ -0,0 +1,100 @@
+// Copyright 2017, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ocgrpc
+
+import (
+	"strings"
+
+	"go.opencensus.io/trace"
+	"go.opencensus.io/trace/propagation"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/stats"
+)
+
+// clientTraceHandler is a an implementation of grpc.StatsHandler
+// that can be passed to grpc.Dial
+// using grpc.WithStatsHandler to enable trace context propagation and
+// automatic span creation for outgoing gRPC requests.
+type clientTraceHandler struct{}
+
+type serverTraceHandler struct{}
+
+const traceContextKey = "grpc-trace-bin"
+
+// TagRPC creates a new trace span for the client side of the RPC.
+//
+// It returns ctx with the new trace span added and a serialization of the
+// SpanContext added to the outgoing gRPC metadata.
+func (c *clientTraceHandler) TagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
+	name := "Sent" + strings.Replace(rti.FullMethodName, "/", ".", -1)
+	ctx, _ = trace.StartSpan(ctx, name)
+	traceContextBinary := propagation.Binary(trace.FromContext(ctx).SpanContext())
+	if len(traceContextBinary) == 0 {
+		return ctx
+	}
+	return metadata.AppendToOutgoingContext(ctx, traceContextKey, string(traceContextBinary))
+}
+
+// TagRPC creates a new trace span for the server side of the RPC.
+//
+// It checks the incoming gRPC metadata in ctx for a SpanContext, and if
+// it finds one, uses that SpanContext as the parent context of the new span.
+//
+// It returns ctx, with the new trace span added.
+func (s *serverTraceHandler) TagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
+	md, _ := metadata.FromIncomingContext(ctx)
+	name := "Recv" + strings.Replace(rti.FullMethodName, "/", ".", -1)
+	if s := md[traceContextKey]; len(s) > 0 {
+		if parent, ok := propagation.FromBinary([]byte(s[0])); ok {
+			ctx, _ = trace.StartSpanWithRemoteParent(ctx, name, parent, trace.StartOptions{})
+			return ctx
+		}
+	}
+	ctx, _ = trace.StartSpan(ctx, name)
+	return ctx
+}
+
+// HandleRPC processes the RPC stats, adding information to the current trace span.
+func (c *clientTraceHandler) HandleRPC(ctx context.Context, rs stats.RPCStats) {
+	handleRPC(ctx, rs)
+}
+
+// HandleRPC processes the RPC stats, adding information to the current trace span.
+func (s *serverTraceHandler) HandleRPC(ctx context.Context, rs stats.RPCStats) {
+	handleRPC(ctx, rs)
+}
+
+func handleRPC(ctx context.Context, rs stats.RPCStats) {
+	span := trace.FromContext(ctx)
+	// TODO: compressed and uncompressed sizes are not populated in every message.
+	switch rs := rs.(type) {
+	case *stats.Begin:
+		span.SetAttributes(
+			trace.BoolAttribute{Key: "Client", Value: rs.Client},
+			trace.BoolAttribute{Key: "FailFast", Value: rs.FailFast})
+	case *stats.InPayload:
+		span.AddMessageReceiveEvent(0 /* TODO: messageID */, int64(rs.Length), int64(rs.WireLength))
+	case *stats.OutPayload:
+		span.AddMessageSendEvent(0, int64(rs.Length), int64(rs.WireLength))
+	case *stats.End:
+		if rs.Error != nil {
+			code, desc := grpc.Code(rs.Error), grpc.ErrorDesc(rs.Error)
+			span.SetStatus(trace.Status{Code: int32(code), Message: desc})
+		}
+		span.End()
+	}
+}